Several communication systems and applications use frequency division multiple access (FDMA) schemes for allocating frequency resources to multiple communication terminals. One type of FDMA is orthogonal frequency division multiple access (OFDMA), which is used, for example, in communication systems based on the IEEE 802.16 family of standards, commonly referred to as WiMAX. Information regarding these standards is available at www.ieee802.org/16 and at www.wimaxforum.org.
Mobile WiMAX applications often conform to the IEEE 802.16e standard, entitled “Amendment to IEEE Standard for Local and Metropolitan Area Networks—Part 16: Air Interface for Fixed Broadband Wireless Access Systems—Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands,” which is incorporated herein by reference. Sections 8.4.1, 8.4.2, 8.4.3, 8.4.4, 8.4.6.2, 8.4.6.3 of the standard describe uplink signal generation and transmission.
OFDMA signals comprise multiple subcarriers and, as such, often have large peak-to-average power ratios (PAPR). Some methods and systems have been proposed for transmitting signals having single-carrier characteristics and lower PAPR within the framework of OFDMA. Such methods and systems include, for example, interleaved OFDM, also referred to as I-FDMA and single-channel FDMA (SC-FDMA). These methods and signals are described, for example, by Klang et al. (editors), in “Identification of Radio-Link Technologies,” Deliverable D2.1 of the Wireless World Initiative—New Radio (WINNER), IST-2003-507581, version 1.0, Jul. 16, 2004, which is incorporated herein by reference. I-FDMA, also referred to as Frequency Domain Orthogonal Signature Sequences (FDOSS), is described in section 3.2.15, pages 91-92 of this reference. SC-FDMA is described in section 3.2.16, on page 93.